Reciprocating electromagnetic motor



June 7, 1949. v McHENRY 2,472,334

RECIPROCATING ELECTROMAGNETIC MOTOR Filed Sept. 18, 1947 INVENTOR.

WITNESS.- f womw Patented June 7, 1949 RECIPROCATING ELECTROMAGNETIC MOTOR nanan'a 1.. Mciiefniy, Sayre, Pa., signer to Ben'di'ii: Aviation Corpdi'ation, a corporation of Delaware Application September 18, 1947, Serial No. 774,725

" (Cl. m me The present invention relates to a reciprocating electromagnetic motor for pumps and the like and more particularly to the controlling mechanisih therefor.

Various forms of electromagnetic motors incorporafing a reciprocating actuated lrn n t have been devised in which a solenoid is used as an actuator, and the intermittent energiza'tidn or the solenoid eifectuated by contacts which are controlled in various ways by the actuated element. When such control has been by magnetic means, involving variations in air gaps in a magnetic circuit, difi'iculties have been encountered in obtaining adequate -cor'i'tact pressure and reliability of operation,

It is an object of the present invention to provide a novel electromagnetic motor which is simple in construction and e'fiicient and reliable in operation.

It is another object to provide such a device including a magnetic control of the actuating contacts.

It is another object to provide such a device in which the opening and closing of the actuating contacts is by means of branch magnetic circuits which are in shunt with each other whereby the weakening of the flux through one branch causes an increase in 'flux in the other branch, thus insuring positive and effective actuation of the contacts.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing, in

which:

Fig. 1 is a substantially mid-sectional View of an electromagnetic pump structure incorporating a preferred embodiment of the invention; and

Fig. 2 is a section taken substantially on the line 2-'-2 of Fig. 1.

In Fig. 1 of the drawing, there is illustrated a cylinder l of non-magnetic material in which a magnetic 'piston 2 is slidably ino'unted. A spring 3 is arranged to urge the piston toward the upper end of the cylinder, and a solenoid 4 surrounding the cylinder is efiective when energized to retract the piston against the force of the spring 3.

Circular pole pieces 5 and 6 surround the cylinder l adjacent the ends of the solenoid 4, and a casing I of magnetic material is arranged to enclose the entire structure and to furnish a return path for the flux of the solenoid.

Means for energizing the solenoid to actuate the pump are provided comprising a battery 8 grounded at 9 and connected through a switch ,II and lead [2 to one terminal or the solenoid.

,iapbs'ite terminal of the solenoid is connected by a lead I3 to a fixed "contact [4 '(Fig. 2) and a mov' ble contact I5, which 'is grounded as indicated at It, is aaaetea to be brougntfintp engagement with the fixed contact I'4 'to "compute the energizing circuit for the solenoid 4.

Means for actuating the contact '15 to cause reciprocation of the piston 4 is provided can .1. I. by 2 ll. Electromagnet ll is composed of a stationary part is and a movable part 49 pivoted thereto as indicated at 2!. The parts T8, 19 are con "ntously magnetized during actuation or the pump by means of 'a coil 22 connected at one 'h'd'tothe battery lead 'I 2, and having its other end grounded V as shown at 23. 1 I

The stationary part I 8 of the eiettronagfiet 11 is formed with 'a block 24 or magnetic material conforming interiorly to the outer wall or the cylinder I, and 'exter'iorly to the inner wall of the casing l. The free end of the movable part f9 of the electromag'net is also formed 'as a block '25 the inner end of which conforms to the outer suriace oi the cylinder l "and is located substantially uia'metrican' with respect teth'e block 2'4. The block 25 is formed at i s outer end with a convex surface 26 located adjacent the inner wall or the casing but spac'ed inwardly therefrom, A curved abutment member 21 of non-magnate material limits the travel of the block 25 outwardly toward the wall of the casing.

Th'e movable Contact [5 is carried byfan arin 23 fixed as indicated 'at '29 to th e blo'ck 25 soth'at pivotal movement of the block 25 and part 19 of the 'electromagne't cause's the contact 15 to more iiit'o and out of engagement with the fixed con'tadt l in the operation or this device, starting with the parts in the positions shown in Figs. 1 and '2, closure of the manual switch I] c auses energia'atioh of the electromagnet i7. Since the piston 2 is at the upper end of its stroke. it closes the gap between the magnetic blocks 24, 25 except for the thickness of the walls of cylinder I, so that the flux of the ele-ctromagnet I! flows from one block to the other through the piston 2 causing the block 25 to be strongly attracted to the piston, thus holding contact [5 in engagement with contact 14. The solenoid 4 is thus energized from the battery 8 whereby the piston 2 is retracted downward against the spring 3 until it is drawn away from the zone of magnetic blocks '24, 25. When this happens, the air gap formed between the magnetic blocks 24, 25 becomes greater than the gap between the surface 26 and the interior of the casing l, The flux of electromagnet ll thereupon is diverted from the direct path through the cylinder and flows through the easing i and across the gap to the surface 26 of magnetic block 25 whereby the latter is attracted outwardly toward the casing until stopped by the spacer 2 thus opening contacts I4, l5.

When the solenoid i is thus deenergized, the spring 3 becomes effective to actuate the piston 2 which moves upwardly until its upper end again bridges the space between the magnetic blocks 2t, 25. The reluctance of the shunt magnetic path from block 24 through the piston to block 25 is thereby lowered so that most of the flux follows this path. The block 25 is thus attracted inwardly until it engages the cylinder i, whereby the contacts [4, I5 reclose, and the operation is repeated.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and changes may be made in the form and arrangement of its parts Without departing from the spirit of the invention as defined in the following claims.

What is claimed is:

1. In an electromagnetic reciprocating motor, a cylinder of non-magnetic material, a piston of magnetic material slidably mounted therein, a spring for actuating the piston in one direction, a solenoid arranged when energized to move the piston against the force of the spring, means for controlling the energization of the solenoid including a fixed contact, a movable contact, a magnetized member carrying said movable contact pivotally mounted for movement toward and away from the cylinder, means for completing a circuit for the flux of said magnetized member including the piston in the cylinder and means for providing a shunt path for said flux which does not include said piston.

2. An electromagnetic motor as set forth in claim 1 in which said shunt path includes an air gap which is substantially greater than twice the thickness of the cylinder wall, but less than the diameter of the piston.

3. An electromagnetic motor as set forth in claim 2 in which the shunt magnetic circuit is composed of magnetic material except for said air gap and the pivotal mounting of the magnetized member.

4. In an electromagnetic reciprocating motor, a cylinder of non-magnetic material, a piston of magnetic material slidably mounted therein, a spring for actuating the piston in one direction, a solenoid arranged when energized to move the piston against the force of the spring, a casing of magnetic material surrounding the solenoid, means for controlling the energization of the solenoid including a fixed contact, a movable contact, a magnetized member carrying said movable contact pivotally mounted for movement toward and away from the cylinder, means for completing a circuit for the flux of said magnetized member including the piston in the cylinder, and a shunt path for said has including said casing and an air gap between the casing and the magnetized member.

5. In an electromagnetic reciprocating motor, a cylinder of non-magnetic material, a piston of magnetic material slidably mounted therein, a spring for actuating the piston in one direction, a solenoid arranged when energized to move the piston against the force of the spring, means for controlling the energization of the solenoid including a fixed contact, a movable contact, a magnetized member carrying said movable contact pivotally mounted for movement toward and away from the cylinder, means for completing a circuit for the flux of said magnetized member including a block of magnetic material in contact with and conforming to the interior of the casing and the exterior of the cylinder, and connected to the pivoted end of the magnetized member, the free end of the magnetized member conforming with and adapted to engage the exterior of the cylinder substantiall opposite said block.

6. An electromagnetic motor as set forth in claim 5 in which said free end of the magnetized member also has a pole piece extending toward the wall of the casing.

7. In an electromagnetic reciprocating motor, a cylinder of non-magnetic material, a piston of magnetic material slidably mounted therein, a spring for actuating the piston in one direction, a solenoid arranged when energized to move the piston against the force of the spring, means for controlling the energization of the solenoid including a fixed contact, a movable contact, a magnetized member carrying said movable contact pivotally mounted for movement toward and away from the cylinder, means for completing'a circuit for the flux of said magnetized member including the piston in the cylinder and means for providing a shunt path for said flux which does not include said piston; in which the magnetized member is shaped to conform to the cylinder, and when in contact therewith, the magnetic circuit through the piston is completed through magnetic material except for the walls of the cylinder and the pivotal mounting of the magnetized member.

HARLAND L. McHENRY.

REFERENCES CITED The following references are of record in the file of this patent: 

